Apparatus for delivery of gas and air to furnaces



G. KEITH. APPARATUS FOR DELIVERY OF GAS AND AIR TO-FURNACES. APPLIQIATION FILED OCT. 14. I918. k 3,513 Patented Dec. 28,, 11920.

2 SHEETS-SHEET I.

G. KEITH. APPARATUS FOR DELIVERY OF GYAS AND AIR T0 FURN ACES.

APPLICATION FILED OCT. I4, IQIB- I 1,363,51@ Patented Dec. 28, 1920..

2 SHEETS-SHEET 2.

GEORGE KEITH; OF LONDON, ENGLAND, ASSIGNOR 0F ONE-HALF T0 OF LONDON, ENGLAND.

IVES KEITH,

APPARATUS FOR DELIVERY GAS AND AIR TO FURNACES.

of which the following is a specification.

This invention relates to apparatus for maintaining proportional delivery of gas and air supplied through separatepassages to gas-fired furnaces notwithstanding variations in the resistances to'the flow of these fluids or in their relative pressures.

An apparatus according to the invention consists essentially of two movable members,

such-as diaphragms, for example, said diaphragms being operatively connected to each other and to an admission valve for the combustible fluid, one'pair of the opposing sides of said diaphragms being influenced by pressure differences set up by the flow of the comburent fluid, and the otherpair of opposing sides of said diaphragms being influenced by the pressure differences across a manually adjustable member presenting a resistance to the How of combustible fluid whereby the diaphragms are balanced.

In the accompanying drawings, Figure 1 represents diagrammatically one arrangement according to the" invention. Fig. 2 represents a modification.

In the construction shown in Fig. 1 there are connected to the furnace A separate pipes B. and C, hereinafter designated, re-

spectively, the air pipe and the gas pipe, for admission of air and gas.

The portion of the air pipe B next the furnace A may be heated by the waste prod.- ucts of combustion from the furnace, being formed,.for' example, as a coil as shown at B. At a point in the air pipe B in advance of the zone where the air is heated a choke bore D is introduced.

Fitted to the gas pipe C is a governor proilg ided with two connected diaphragms The diaphragms E, F, which are con nected by a rod K, are disposed one on each side of the gas inlet C to which is fitted the butterfly valve L, and a partition N through which'the rod K passes is interposed be tween the diaphragms E, F so as to divide Specification of Letters Patent. Patentigd Der}, 28, 1192(0,

Application filed October M, 1-918. Serial-Ito. 258,064. I

the diaphragm chamber into compart- Vments to one of which is fitted the gasinlet connection C and to the other of which is e is taken to the back of the diaphragm E on the inner face of which diaphragm E presses the gas admitted by the valve L into the first compartment, and from the low pressure side of the air' pipe B, 'e., from the side of the choke bore D nearest the furnace A a connection f is taken to the back of the diaphragm F to theinner face of which latter is transmitted the pressure pre- 1 vailing in the pipe C.

A control valve J fitted to the air pipe B I in advance of the choke bore D (i. 6., more remote from the furnace A than the choke bore D) serves'to regulate the quantity of air supplied.

lt.,will be seen that with \the arrangement described change of pressure in the gas pipe C beyond "the valveH, that is, at the side of the valve H nearest the furnace, will make itself felt on that face of the diaphragm F nearest the partition N, the combined effect of which and of the influence on the gas pressure set up by the governor on the other side of the valve H in consequence of the difference of pressure prevailing on the two'sides of the choke bore is to maintain across the valve H a difference of pressure equal-or proportionate to the difference of pressure across the choke bore D. It follows that the proportions of gas and air admitted to the furnace will be maintained constant notwithstanding variation of the re sistance in either pipe or in the furnace or of other conditions which would ordinarily re-- sult in fluctuation of the proportions.

It will be seen that in the construction shown in Fig. 1 the static pressure of the air on one side of either diaphragm may be quite'high compared with the static pressure phragm.

the diaphragm E being exposed to air pres- D or its equivalent. In this arrangement sure and both sides of the diaphragm F being exposed to gas pressure. With the rearrangement 9f the tubular connections =e and f as shown in Fig. 2 the static pressure ofthe air may be as high as .required: but the difference of pressures on the two sides of the diaphragm Ewill only be equal to the difference of the pressure on the one side and the pressure at the throatof the choke bore also change of pressure in the gas plpe C beyond the valve H will make itself felt 'on the face of the diaphragm F nearest the partition N, any rise of pressure in the pipe C beingadded to the pressure set up by the governor. N j

In practice, it is found that the sensitive. ness of the apparatus' is much improved when the stroke of the diaphragm is kept as short as possible, so as to reduce any stretching effect on the diaphragms or excessive puckering in the transition from one extreme position to the other. v

To attain this desirable result, the modified governor valve arrangementshown in Fig. 2 may be adopted, the arrangement including a relay so that the governor valve ma be operated with minimum force.

s shown, the governor valve consists of a diaphragm valve L which is adapted to bear on a valve seating L'-, and at'the back .of which is a diaphragm chamber L into which is a small leak L from the gas supply admitted through-the pipe connection C.

Centrally of'thediaphragm L is a small relay valve L operable directly by the governor diaphragms E, F through the rod L.

Itwill be evident that,-as soon as the opening of the relay valve'L" permits the pressure on the back of the diaphragm L to fall by permitting the passage of a quantity of gas in excess of what can pass through the leak- L, the pressure of the gas acting on the exposed annular surface of the diaphragm will open the valve L, and that, conversely,

when the relay valve L closes, the gas passlng through the leak L will exercise pressure on the back of the diaphragm valve L '50 as to close the latter. That is, the movement of the diaphragm valve L simply follows the movement of the relay valve L The contraction at D of the passage through the pipe B may be in effect a venturi arrangement.

In the construction'shown in Fig. 2 the connection e is taken from a point on the high pressure side of the contraction and the connection f taken from the throat, the end of the connection 6 which enters the air pipe B being turned to facefthe stream and gas and air be delivered under pressure or be .drawn in .by the suction eifect'of the flue or otherwise.

For the purpose of the foregoing explanation it is assumed that the fluids to be handled are gas and air. By the term gas'it is intended to -include also hydrocarbon and other combustible vapors; oxygen may also be utilized as a supporterof combustion.

What I' claim is 1. Apparatus. for maintaining the proportional delivery of a combustible fluid and a comburent fluid supplied to a gas-fired 'furnace, consisting of the combination of two movable members in separate compartments, said members being operatively connected to eachv other, an admission valve for the combustible fluid to, which valve said members are also connected, and a manually adjustable device presenting a resistance to the flow of combustible fluid, said movable'members being so arranged that one pair'of the .opposing sides of said members will be in- 'each other, an admission valve for the combustible fluid, arel'ay valve to which said members are also connected, and a manually adjustable device presenting a resistance to the flow of the combustible fluid, said members being so arranged that one of said members Will be influenced by pressure diflerences set up by the flow of the comburent fluid, and the other of said members will 3. Apparatus for maintaining the proportional delivery of a combustible fluid and a comburent fluid supplied to a gas-fired furnace, consisting of two movable elements each having two sides subject to pressure, separate compartments in which said elements are contained, an operative connection between said elements, an admission valve for the controlled fluid operatively connected to said elements. and a manually adjustable device presenting a resistance to the flow of the controlled fluid, said movable elements being so arranged that one pair of opposing ,be influenced by the pressure differences across said resistance.

sides of said elements will be influenced by pressure difl'erences set up by the flow of the controlling fluid, and that the other pair of opposing sides will be influenced by the pressure differences across said resistance so that said elements are balanced.

4. Apparatus for maintaining the proportional delivery of a combustible fluid and a comburent fluid supplied to a gas-fired furnace, consisting of the combination of two diaphragms operatively connected to one another, separate compartments in which said diaphragms are contained, an admission valve for the combustible fluid, a relay valve to which said diaphragms are also connected, an adjustable resistance to the flow of the i phragm being exposed to the pressure of thecombustible fluid on opposite sides of said resistance.

In testimony whereof I have signed .my name to this specification in the presence of 'two subscribing witnesses.

GEORGE KEITH.

Witnesses V KATHARINE 'FOTHERINGHAM, lsAnEL RoLLo. 

